Geomagnetic field and the growth of the Earth's inner core: Past, present and future

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F25%3A00641702" target="_blank" >RIV/67985530:_____/25:00641702 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0031920125001542?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0031920125001542?via%3Dihub</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.pepi.2025.107460" target="_blank" >10.1016/j.pepi.2025.107460</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geomagnetic field and the growth of the Earth's inner core: Past, present and future

Popis výsledku v původním jazyce

Changes in the geomagnetic field corresponding to the Earth's inner core growth are numerically investigated. The Geodynamo is driven by thermochemical convection in the Earth's outer core, with the codensity gradient serving as the primary driving force. Simulations begin with a small inner core ('Past'), which progressively enlarges until reaching a stage where the inner core becomes dominant ('Future'). During the 'Past' stage, the Geodynamo model generates a multipolar geomagnetic field, which gradually transitions into a predominantly dipolar field as the inner core grows. These transitions are also accompanied by shifts between weak-field and strong-field dynamos and vice versa. The ratio of magnetic to kinetic energy emerges as a more reliable parameter for controlling the transition from multipolar to dipolar dynamos. The dipole component for a small inner core proves unstable, with frequent polarity reversals. As the inner core grows, the frequency of these reversals decreases until the 'Present' case, where polarity reversals cease entirely. It is important to note that during the 'Past', fluctuations in dipole polarity are observed even in a dipole-dominated magnetic field. In the 'Future' stage, representing a potential scenario for the Earth's geomagnetic field, the hydromagnetic dynamo produces a dipole-dominated magnetic field without polarity reversals. However, if the Earth's liquid outer core becomes exceedingly small, convection diminishes, causing the Geodynamo to fail. This leads to a slow decay of the magnetic field due to magnetic diffusion. During the 'Future' stage, the emergence of subcritical dynamos is observed. It is important to note that the results of the present analysis are more strongly influenced by the supercriticality of the flow than by the inner core size, as the latter is determined by the selected solution parameters.

Název v anglickém jazyce

Geomagnetic field and the growth of the Earth's inner core: Past, present and future

Popis výsledku anglicky

Changes in the geomagnetic field corresponding to the Earth's inner core growth are numerically investigated. The Geodynamo is driven by thermochemical convection in the Earth's outer core, with the codensity gradient serving as the primary driving force. Simulations begin with a small inner core ('Past'), which progressively enlarges until reaching a stage where the inner core becomes dominant ('Future'). During the 'Past' stage, the Geodynamo model generates a multipolar geomagnetic field, which gradually transitions into a predominantly dipolar field as the inner core grows. These transitions are also accompanied by shifts between weak-field and strong-field dynamos and vice versa. The ratio of magnetic to kinetic energy emerges as a more reliable parameter for controlling the transition from multipolar to dipolar dynamos. The dipole component for a small inner core proves unstable, with frequent polarity reversals. As the inner core grows, the frequency of these reversals decreases until the 'Present' case, where polarity reversals cease entirely. It is important to note that during the 'Past', fluctuations in dipole polarity are observed even in a dipole-dominated magnetic field. In the 'Future' stage, representing a potential scenario for the Earth's geomagnetic field, the hydromagnetic dynamo produces a dipole-dominated magnetic field without polarity reversals. However, if the Earth's liquid outer core becomes exceedingly small, convection diminishes, causing the Geodynamo to fail. This leads to a slow decay of the magnetic field due to magnetic diffusion. During the 'Future' stage, the emergence of subcritical dynamos is observed. It is important to note that the results of the present analysis are more strongly influenced by the supercriticality of the flow than by the inner core size, as the latter is determined by the selected solution parameters.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10508 - Physical geography

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physics of the Earth and Planetary Interiors

ISSN

0031-9201

e-ISSN

1872-7395

Svazek periodika

368

Číslo periodika v rámci svazku

Nov.

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

15

Strana od-do

107460

Kód UT WoS článku

001608567700001

EID výsledku v databázi Scopus

2-s2.0-105020016337